1. Field of the Invention
This invention relates to a navigation apparatus which displays a path to a destination on a map to thereby guide a driver of a vehicle along the path to be followed.
2. Description of the Related Art
The navigation apparatus for a vehicle is configured to show in a display a map on which a navigating path such as a shortest-time path is designated, and/or relevant information, to suggest a road suitable for a driver of the vehicle to drive along. The driver of the vehicle may make predetermined settings at the navigation apparatus in which he/she can select a preferable type of navigating path among various alternatives such as a shortest-time path, a shortest-distance path, and a freeway-detouring path.
Conventionally, the path-finding algorithm for determining a navigating path is based on a single condition, and thus only one navigating path is displayed at the navigation apparatus. In recent years, however, another type of navigation apparatuses, for example as disclosed in [Patent Document 1], proposes that when navigation is started for example by a driver specifying his/her destination at the navigation apparatus, path-finding operations are performed on a plurality of conditions to display a plurality of navigating paths resulting from the operations. This type of the navigation apparatuses allows the driver to check the plurality of navigating paths on the map before selecting a path to be followed among the suggested alternatives.
A still another type of navigation apparatuses, for example as disclosed in [Patent Document 2], proposes a reroute function that permits a driver to change the navigating path from a path which is currently being traveled to another path. With this navigation apparatus having such a reroute function, even when an accident or the like takes place on the navigating path the driver has initially selected, the driver can perform a path-finding operation again on his/her way to set a new path to be followed.
<References Cited>
[Patent Document 1]: JP 2005-17052 A
[Patent Document 2]: JP 2004-61356 A
Incidentally, a driver of a vehicle may wish to change the path-finding condition while driving along a specific navigating path. For example, there is often the case where the driver considers that he/she may use a toll road up to a specific point but does not wish to use one from the specific point onward. What the navigation apparatus disclosed in [Patent Document 1] achieves is merely that a plurality of paths determined on the basis of different path-finding conditions are displayed when the navigation is started at the point of departure or the like. Accordingly, in order to display alternative paths determined on the basis of different path-finding conditions during driving at some midpoint on his/her way to the destination, the driver may be required to stop the vehicle, and then (or even when the driver does not have to stop the vehicle, irrespectively) he/she may be required to operate and instruct the navigation apparatus to perform an updating path-finding operation.
On the other hand, the navigation apparatus disclosed in [Patent Document 2] is configured to automatically execute a reroute operation to display an alternative path when the vehicle is likely to deviate from a navigating path. In this configuration, the driver can follow the alternative path at will. However, the alternative path suggested in this instance is a second path found on the basis of the same condition as that on which the originally suggested navigating path was based. Accordingly, the navigation apparatus disclosed in [Patent Document 2] would not fulfill the driver's need for changing the path-finding conditions (e.g., from a path including a toll road to a path avoiding any toll road).
The present invention has been made in an attempt to overcome the aforementioned drawbacks in the existing technologies. It would thus be considered desirable to provide a navigation apparatus which allows a driver to change a path-finding condition at will without any operation at the navigation apparatus while a vehicle is running along a navigating path suggested on the basis of a specific path-finding condition, and to follow any alternative path suggested on the basis of a different path-finding condition at will.
Illustrative, non-limiting embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an illustrative, non-limiting embodiment of the present invention may not overcome any of the problems described above.